The cDNA of human brain-derived neurotrophic factor (hBDNF) and the fragment encoding mature hBDNF were amplified from human genomic DNA by PCR, and separately ligated into pUC18. Two inserted fragments were analysised by sequencing, which are correct.The expression of the hBDNF was controled by CMV promotor in NIH/3T3 cells transfected with recombinant plasmid, and analysed by RT-PCR, showing existance of BDNF mRNA in cells. The expression product of the mature hBDNF under the control of T7 promotor was in the inclusion body of E.coli, and visualized by SDS-PAGE analysis.